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Question 1

Genetics

Answer 1

Study of what genes, how they carry info, how info is expressed, how genes replicate

Question 2

Gene

Answer 2

Segment of DNA that encodes a functional product, usually a protein
Not all DNA codes for a functional product, only the ones who do are considered genes

Question 3

Chromosome

Answer 3

Structure containing all DNA (junk DNA + genes) that physically carries hereditary info
Contain the genes

Question 4

Genome

Answer 4

All the genetic info in a cell

Question 5

Genomics

Answer 5

Molecular study of genomes

Question 6

Genotype

Answer 6

Genes of an organism, what the gene is

Ex: genotype codes for blue eyes

Question 7

Phenotype

Answer 7

Expression of the genes – physical representation

Ex: phenotype is blue eyes

Question 8

Determining Relatedness

Answer 8

Takes the genetic code of one species and line it up with other species
Compares nucleotide sequence, the more similar in sequence the more related
Determine what percent is identical btwn species

Question 9

Genetic Maps

Answer 9

Cartoon illustration of circle that resembles a bacteria chromosome where all the known genes can be plotted on

Question 10

Central Dogma/Flow of Genetic Information

Answer 10

DNA –> RNA –> Protein
Expression: genetic info is used w/in a cell to produce the proteins. Going from DNA to protein
Recombination: genetic info can be exchanged btwn cells of the same generation so it can evolve. Only way bacteria can exchange genetic info b/c it doesn’t do sexual replication
Replication: genetic info can be transferred btwn generations of cells – parent cell to two daughter cells

Question 11

DNA Structure

Answer 11

Made up of 4 primary nucleotides – A, T, C, G
Double helix associated w/proteins
Backbone is deoxyribose-phosphate (sugar ring)
Strands held together by hydrogen bonds btwn A-T and C-G
Antiparallel: the sugar-phosphate backbone of one strand is upside down relative to the backbone of the other strand
All chemical rxns happen off the 3’ end with the OH (hydroxyl group), a nucleotide cannot connect/add onto the 5’ end with the phosphate group

Question 12

Semiconservative Replication

Answer 12

Conservative b/c each daughter cell will have 1 original DNA strand from the parent cell (conservative) but only SEMI-conservative b/c the other strand which is the new strand will just be a copy of the original strand

Question 13

DNA Replication - General

Answer 13

Binary Fission
Takes the double helix and pulls it apart and makes a copy by adding in the appropriate nucleotides to each of the daughter strands. End up producing two identical strands

Question 14

DNA Polymerase

Answer 14

Enzyme that catalyzes the hydrolysis rxn that adds on a nucleotide each time
Takes DNA and makes a DNA copy

Question 15

DNA Replication - Process

Answer 15

1) Replication Bubble, Replication forks
2) Replication begins at the Ori (origin)
3) Top strand runs from 5’ to 3’, Bottom strand runs from 5’ to 3’
4) DNA Polymerase starts laying a new nucleotide over and over as the bubble keeps on the top strand – Leading Strand
5) On the bottom strand – Lagging Strand, an RNA Primer (there are multiple RNA Primers) is laid close to the bubble that has a 3’ OH hanging off it that DNA Polymerase needs to add a nucleotide. DNA Polymerase will add nucleotides behind each RNA Primer. RNA Primer + DNA that has been filled in behind it = Okazaki Fragment. Once there is a complete Okazaki Fragment, DNA Polymerase (DNA Ligase) will remove the RNA Primer and use the 3’ OH that is available due to the DNA that has already been put in, and fill that back in resulting in a complete strand of DNA

Question 16

DNA Replication - Summary

Answer 16

1) Replication Bubble, Replication forks
2) Replication begins at the Ori (origin)
3) Leading Strand: Top 1/2 of strand goes 5’ to 3’, there is a 3’ OH so DNA Polymerase can just follow the bubble and keep adding in nucleotides as the bubble continues to open
4) Lagging Strand: On bottom 1/2 of strand, there is no 3’ OH hanging off so an RNA Primer is laid, DNA Polymerase extends that to the next RNA Primer. The RNA Primer + DNA that is laid is called the Okazaki Fragment. Once that is done, the RNA Primer is pulled out and is replaced with DNA

Question 17

Transcription - General

Answer 17

DNA –> RNA (making an RNA transcript of the DNA)
Goal: to make RNA
RNA Polymerase makes RNA
3 Different Types of RNA that can be made: mRNA (ends up becoming protein, messenger RNA), tRNA (specialized little pieces of RNA involved in translation, bring amino acids for translation, transport RNA), Ribosomal RNA (makes up ribosomes, involved in translation

Question 18

Transcription - Process

Answer 18

1) Every gene starts at a Promoter – a specific sequence on the DNA that signals when the gene starts, and ends at a Terminator - specific sequence that tells RNA Polymerase where the gene stops
2) Occurs 5’ to 3’
3) 2 strands are pulled apart
4) Starts at the Promoter, RNA Polymerase binds and moves along in the 5’ to 3’ direction and match each nucleotide to the corresponding nucleotide, but b/c making RNA matches A to Uracil. RNA is single stranded
5) RNA Polymerase ill continue until it reaches the Terminator sequence and then it will disassociate leaving mRNA
In Prokaryotes, mRNA can go directly into translation
In Eukaryotes, there are introns (junk DNA) so before mRNA can enter translation, the introns must be cut out

Question 19

Translation - General

Answer 19

RNA –> Protein

Question 20

Translation - Process

Answer 20

1) DNA sequence – 4 nucleotides A, U, G, C
2) 70S Ribosome reads in sets of 3 known as codons and adds the amino acid a codon codes for
3) Starts at the start codon (AUG)
4) Each codon codes for a specific amino acid
5) Ribosome knows when to stop adding amino acids to make proteins when it reaches a stop codons/nonsense codon
64 different codons, multiple codons can read for the same amino acid

Question 21

Why is genetic code considered “degenerate”?

Answer 21

B/c the first two letters in the codon are identical but the last is different. important b/c if the cell messes up and puts in the wrong letter in the 3rd position, it will still make the same amino acid – way for the cell to self-regulate against mutation
If amino acid is wrong, can change the whole functionality of the protein

Question 22

Translation - Summary

Answer 22

1) mRNA comes off in transcription, ribosome starts scanning it looking for the start codon
2) Once start codon is located, ribosome clamps down on it, tRNA will bring in a complementary anticodon that will pair w/the codon on the mRNA, resulting in an amino acid
3) Ribosome keeps moving down the mRNA, reading in sets of 3, each set of 3 a new tRNA (are recycled) comes in, matches its anticodon to the codon and adds on the new amino acid
4) Keeps going until Ribosome reads a stop codon/nonsense codon, ribosome disassociates, mRNA is done, leaves a new protein that can fold into a secondary and tertiary structures

Question 23

Genetic Expression

Answer 23

Transcription and Translation

Question 24

Constitutive Gene

Answer 24

Always on, expressed at a fixed rate

Question 25

Repressible Gene

Answer 25

Default in on, if not needed it can be turned off
Genes involved in anabolic rxns
Exs: tryptophan, glycine

Question 26

Inducible Gene

Answer 26

Default is off, if needed can be turned on
Genes involved in catabolic rxns
Ex: genes involved in breaking down mannose

Question 27

Operon

Answer 27

Overall components that make up a gene
Promoter, Operator, structural genes
RNA Polymerase binds to Promoter and Operator

Question 28

Induction

Answer 28

Default being blocked by a repressor unless the inducer that removes the repressor is present and then RNA Polymerase can then make copies of the gene

Question 29

Repression

Answer 29

Default is on, no repressor. But if there is too much of the repressible gene, the gene will bind to repressor protein, the shape will change and RNA polymerase can no longer make more of the repressible gene

Question 30

Mutation

Answer 30

Change in the genetic material

Can be beneficial, harmful, or neutral

Question 31

How do mutations occur?

Answer 31

2 ways:

1) Exposure to a mutagen (outside force)
2) Spontaneous mutation

Question 32

Mutagen

Answer 32

Outside force that causes a mutation

Question 33

Point Mutation

Answer 33

One nucleotide gets changed

Different types of point mutations

Question 34

Missense mutation

Answer 34

One nucleotide is changed

Point mutation that alters the function of the protein but does not destroy it

Question 35

Nonsense mutation

Answer 35

Inserts a stop codon in the middle of the protein

Point mutation that alters the function of the protein and destroys it

Question 36

Frameshift mutation

Answer 36

NOT a point mutation

One nucleotide pair is inserted or removed. Destroys the protein

Question 37

Spontaneous mutation

Answer 37

Occur from DNA and RNA Polymerase causes it by accident

Rarely happens

Question 38

Chemical Mutagens

Answer 38

Chemical mutagen is defined as causing a mutation every 1,000 base pairs
Analogs that look similar enough to a nucleotide that it fools DNA Polymerase or RNA Polymerase into using it

Question 39

Ionizing Radiation

Answer 39

Has a short wavelength, packs a lot of energy, can cause rearrangment of electrons

Question 40

UV Radiation

Answer 40

Can cause mutations and skin cancer
When there are two thymines next to each other that are supposed to be hydrogen bonded to adenines. when UV radiation hits it, it breaks the hydrogen bonds and causes the two thymines to double bond to each other. Causes DNA to bubble up. When DNA or RNA Polymerase comes along, it gets stuck at the bubble and cannot go any further. Whatever gene it is encoding for, the body can no longer make.

Question 41

Repair

Answer 41

Nucleotide Excision Repair: photolyase separates thymine dimers and fill it in with new DNA to repair it

Question 42

Vertical Gene Transfer

Answer 42

Sexual reproduction – direct exchange of genetic info

Bacteria cannot do this

Question 43

Horizontal Gene Transfer

Answer 43

Exchanging genetic info btwn parent cells
Only way bacteria can vary their genetic info which is important for evolution
1) Recombination
2) Transformation
3) Transduction

Question 44

Recombination

Answer 44

Cell shares w/itself

Exchange of genes btwn 2 DNA molecules in a cell

Question 45

Transformation

Answer 45

Uptake of naked DNA (not associated w/anything)

Question 46

Conjugation

Answer 46

Cell to Cell DNA transfer
Some cells are F+ cells – have the conjugation plasmid separate from its genome (circular piece of DNA that codes for the pili gene). All other cells are F- and do not have the plasmid. An F+ cell sends its DNA/conjugative plasmid over to the F- cells through its pili. The F- cells turn to F+ cells
Considered a sexual process, not reproduction, b/c there is a direct exchange of genetic info
Important b/c a lot of the genes found on the F+ plasmid are antibiotic resistant and can conjugate w/other bacteria in the body and give them antibiotic resistance too
Different species can conjugate w/each other

Question 47

Transduction

Answer 47

Transfer of DNA via a virus
A phage (virus) attacks and injects its DNA into the bacteria
The virus will reproduce w/in the bacterial cell
When its done reproducing, it makes adult viruses again that will burst out of the cell
Sometimes when the virus packages up its viral DNA it takes some of the bacterial DNA w/it, so when the virus attacks another bacterial cell it gives that cell not only the viral DNA but the bacterial DNA
So it is allowing genetic exchange btwn two bacteria, b/c bacterial cell now has a new set of bacterial genes that it can choose to include in its chromosome